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    <title>Document</title>
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    <script>
      var a1 = new Number(10); //object
      var a2 = 10; //number
      console.log(a1, a2);
      console.log(typeof a1, typeof a2); //typeof用于获取数据类型
      console.log(a1 == a2); //true  ==:只比较值，不比较数据类型
      console.log(a1 === a2); //flase  ===：即比较值，又比较类型
      var obj = {
          sno:'007',
          sname:'张三'
      };
      //log 以日志的方式显示，info以消息的方式显示
      console.info(obj ,typeof obj);
    </script>
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